<?php
define("TOKEN","1990c"); //TOKEN值
$wechatObj = new wechat();
$wechatObj->valid();
class wechat {
    public function valid() {
        $echoStr= $_GET["echostr"];
        if($this->checkSignature()){
        echo$echoStr;
        exit;
         }
}
 private function checkSignature() {
        $signature= $_GET["signature"];
       $timestamp= $_GET["timestamp"];
       $nonce= $_GET["nonce"];
        $token= TOKEN;
        $tmpArr= array($token,$timestamp, $nonce);
        sort($tmpArr);
        $tmpStr= implode( $tmpArr );
        $tmpStr= sha1( $tmpStr );
        if($tmpStr == $signature) {
                return true;
   } else {
    return false;
}
}
}
?>